Salivary secretion control

Saliva secretion is ensured by three pairs of large salivary glands and a number of small salivary glands that are scattered throughout the oral cavity. It is triggered reflexively by the autonomic nervous system.

Stimuli inducing secretion

visual,
olfactory,
taste,
mechanical (e.g. food touches the mucous membrane, chewing),
conditioned reflexes,
others (e.g. talk about food).

Secretion suppressing factors

dehydration,
fatigue,
sleep,
fear.

Control Mechanisms

Saliva secretion is stimulated by sympathetic and parasympathetic. The parasympathetic effect is more pronounced.

Parasympathetic

Acetylcholine is released from the endings of parasympathetic fibers, which binds to muscarinic G-protein coupled receptors.
Phospholipase C is activated, which further cleaves phosphatidylinositol-4,5-bisphosphate (PIP₂) stored in the membrane to inositol-1,4,5-triphosphate (IP_{3< /sub>)} and diacylglycerol (DAG).

IP₃ binds to Ca²⁺ channels of the endoplasmic reticulum, opens them and Ca²⁺ flows into the cytosol. This increases the cytoplasmic concentration of Ca²⁺, which leads to an increase in the permeability of ion channels. A thin watery saliva with a slightly increased content of α-amylase is produced.

Acetylcholine also increases the release of kallikreins. Kallikrein converts plasma kininogen to bradykin. It dilates blood vessels and thus increases blood flow, which is necessary for the production of saliva.

Sympathizer

Noradrenaline binds to β₂-adrenergic receptors'. Adenylate cyclase is activated, which converts ATP to cAMP. cAMP activates protein kinase A catalyzing protein phosphorylation. The result is viscous saliva rich in mucin.

Links

References

KITTNAR, Otomar. Lékařská fyziologie. 1. edition. Grada, 2011. 790 pp. ISBN 978-80-247-3068-4.

SILBERNAGL, Stefan – DESPOPOULOS, Agamemnon. Atlas fyziologie člověka. 6. edition. Grada, 2004. 448 pp. ISBN 978-80-247-0630-6.

TROJAN, Stanislav. Lékařská fyziologie. 4. edition. Grada, 2003. 772 pp. ISBN 80-247-0512-5.